- Only set i_offset in the parent directory's i-node during a lookup for

- Only set i_offset in the parent directory's i-node during a lookup for
  non-LOOKUP operations.
- Relax a VOP assertion for a DELETE lookup.  rename() uses WANTPARENT
  instead of LOCKPARENT when looking up the source pathname.  ufs_rename()
  uses a relookup() to lock the parent directory when it decides to finally
  remove the source path.  Thus, it is ok for a DELETE with WANTPARENT set
  instead of LOCKPARENT to use a shared vnode lock rather than an exclusive
  vnode lock.

Reported by:	kris (2)
Reviewed by:	jeff